As is known, endoscopic technique was developed in the medical field with the aim to reduce, as far as it is possible, the necessity of conventional surgical operation in the course of diagnostic procedures, and to limit, at the same time, patient discomfort, recovery time and possible side effects.
To these purposes there are known various endoscopic instruments which are driven directly by the surgeon to advance into the body of the patient. Frequently, body cavities, which said instruments must traverse, are extremely meandering and brittle at the same time, so that from one side a high skill of the surgeon driving the instrument is required, while, from the other side endoscopic diagnostic or surgical procedures are often unfeasible due to the extreme difficulty of performing them. To obviate these inconveniences it has been suggested the use, in endoscopic procedures, of a robot having an autonomous ability to move within the body cavities of a patient and to adapt its configuration to that of the surrounding environment. All necessary surgical and/or diagnostic instruments such as micro-arms, microcameras, and laser emitters can be secured to this type of robot.
Endoscopic robots of the above specified type are known, which, once they are inserted in a body cavity of the patient, move therein with a "snake" or "tentacle" or "elephant trunk" or "inchworm" locomotion mode. These robots have a limited number of degrees of freedom, that is self-bending is allowed in more than one direction with respect to the advancing direction, optionally combined with a rotation about its own axis.
To enable the above mentioned robot to advance in a body cavity of a patient a large amount of air must be blown into the cavity to cause a sufficient widening of it to permit the passage of the robot.
The above advancement mode is painful for the patient as the inspected cavity can be subjected to unnatural expansions. Furthermore, the active means for bending the robot are usually brittle and expensive and increase the size of the robot thereby limiting the possibilities of use.
U.S. Pat. No. 5,337,732 (Grundfest et al.) discloses an endoscopic robot having a redundant number of degrees of freedom and being constituted by a series of mutually articulated rigid segments, designed for being passively bent with respect to one another as a result of the robot locomotion in the cavity. To this purpose the robot has a inchworm-like locomotion mode and anti-slippage means between robot and cavity formed, as an alternative or in combination, by inflatable balloons, blade-like members, protruding and retractable arch members.
The above mentioned anti-slippage means result in a direct interference against the walls of the cavity on which an outwardly pushing action is exerted; the interference may cause an intense pain to the patient as well as a damage to the tissues.
Furthermore the anti-slippage means do not assure a proper durable anchorage to the cavity walls, but only an increased friction due to the force exerted against the walls. For this reason the above endoscopic robot must be equipped with a plurality of anchoring means which, unavoidably, increase its length and, consequently, the discomfort of the patient.